System for recovering water from exhaust gas



Nov. 8, 1949 P. A. PITT ETAL 2,487,176 I SYSTEM FOR RECOVERING WATERFROM EXHAUST GAS Filed April 24, 1945 IN V EN TORS.

o i8 23 PAUL A. PITT. 3 CLARENCE O. MOE. J I 1 ATTORNEY.

Patented Nov. 8, 1949 SYSTEM -.-FOR;RECOVERINGI WKIERLv FROM;

EXHAUST :B'aul; A. PituiSamDiego, andzfllarence 0. Moe; *Ghula- Vista;Galif assignors'ito; SolarAircrafta Company, :San Diego, Calif., acorporation of California.

Application April '24, 194'55- serial 'Noi" 5905036" 2. Claims;01.183921) This-invention relates itozthe oondensationrand'recovery*ofi'watercvapor from ..gases,,and is, particularly: applicableto; the recovery: of the water '7 of "combustion from. the atexhaust gas2011 an aircraft 1 engine;

High efliciency; high duty, internalzcombustion to the operatingtemperature and octane: rating of the fuel employed i that 'thedetonating point is approached veryclosely during normal operation ofthe; engine" with; optimum :mixture; of: fuel "an'd airfor higheificiency. Asaresult, whentthe engine -must be operated at greater:power; output thamnormal; 'knockingresults unless, some other factori'sintroduced'lto' preventzit;

It is well known that knockingwan: be: pre- -vented' under excessiveloa'diby enriching :the'sfuel mixture, and it has been common practiceat!) prevent knocking by enriching the mixture whenflthe engine mustbeoperated under maximum: load for relatively short periods oftime;However, this method is objectionable for several reasons,;one

of" which is-theexcessive fuel consumption. A rich mixture reducesthetendency toward knocking-becauseof the coolingefiect ofith'eiexcessfuel that is introduced into the cylinders; "and, it.' is

"known that tliis cooling effect can beaobtainedhy introducing liquids-=other than fuel; Qne' such liquid is'water, and itisknown that-:- theintroduction ofwater or-watervapor alongt-with' the fuel functionsefiectively to'preventv knocking;

Hereto'fore', however, it'has'often beentimprac- 'tical to use water forthis pur'posebecause' ofsth'e weight or thewater that: would have to becar- =ried' ona fiight 'of appreciable length 0minvention is primarilyfor the' 'purpose of providing 'wat'er onan aircraft for usei in theengines to control knocking; and. we'obtain this water by recovering itfrom the exhaust" gas of the-engines. 'Thewater present in the exhaustgas of an engine results from the combustion of hydrogen in'the 'fuel'with--oxygen from 'therair used'to burn the='fuel', and'the'totalamountot water resulting-*fromcombustion is somewhat in excessof the fuel consumed, with fuels that" are incommon'use.-

An object of the present invention:isto'zprovide internali combustionengines; which: apparatusazis slight/enough: to. permit its advantageousi 11563 011 aircraft.

Another" object is to: provide'zrelativelypompact l apparatus:forrecovering water from the-exhaust gas of! internal:combustionzengines.

Briefly; we attain the foregoing: obj BCtSTi byras- *pirating'exhaustr'gas intoaaa precipitating chamber by means of a spray of cool:water', causing:: -the mixture of i spray water and' exhaust gas-:to:ro'tate rapidly in the precipitating chamber to effect separation :ofwater fromcthe gas by centrifugal "action, discharging: therresidualexhaustgasitrom the chamber at super-ambient pressure; withdrawing the:water/fromthe precipitating -."cham- :ber, -further-cooling; a" portion:of the water in a 7 heat exchanger cooled by thezambient air; andrecirculating the cooled water. under substantial pressure to thespraymeans.

T-WO. resultsare achieved by aspirating ithe wet exhaust gas into theprecipitating chamber with jetsof the-cooling water. Oneresultisthezintimate mixture of the cooling wat'erfwith'theexhaust gas to=chill the latterbelowthe: dewv point andcause condensation of the-watervaporin the gas. The other result is the introduction; of 1c haust 'gas'into the precipitating chamber at a pressure substantially above theambient: pressure without building up undesirable back'pre'ssure: in theexhaustline. We have found that the proportion of the water that. can becon- 'densed from the exhaust gas at azgiven temperat'ure increasesrapidly with the-pressure, so that a 'substantial' increase in theamount of water recovered from the exhaust'ishad by maintaining thepressure within the precipitation chamber above the ambient pressure.

A run understanding of our inventionmay be -'had 'from thefiollowingdetailed descriptionwhich refers'to the drawing, in which:

Fig; l is a perspective view: with parts 5 broken away showing oneembodiment c'fthe invention;

'FigaZ is an enlarged perspective" view showing a portion of theprecipitating chamber; and

Fig; 3 .is' a longitudinal 's'ectional" view through one o'ftthessprayunits. emplbyedinFig; l.

Referring 'to Fig. 1', .therezis shown axpre'cipitat- *i'ngchamber'in/the t'form "of a: cyclone separator iuwintowhichuwetexhaustzgas and water are introduced; and from whichrresidu'al exhaustgas and water. area separately' -withdrawn. Theirwet exhaustgasis:suppliedffromathcx engines through am exhaustczpipe Muwhichfiaedsinto 13a pain'aof rbnanchr pipes 114-42 which extendiato .diametriercallyvoppositb: sides ofi thee cyciionemi branch I2 is furthersub-divided into two branches |3|3 which feed into the sides of separateaspirating units I5. The two aspirating units associated with one of thebranches l2 are horizontally positioned, one above the other, and extendinto an upper cylindrical side wall portion I6 of the cyclone Itangentially. The other two aspirating units associated with the otherbranch I2 are similarly positioned with respect to each other but areconnected to the side wall 16 at a diametrically opposite point and aredirected oppositely so that the fluid introduced into the cyclonethrough all of the units I causes the mixture to whirl in one directionwithin the cyclone.

The aspirating units I5 act as boosters to assist the exhaust gas fromthe branch pipes l3 into the cyclone, so that an appreciable pressurecan be maintained within the cyclone without introducing back pressurein the exhaust line H extending from the engine. The motive poweremployed to pump the gas is water under pressure supplied to jets withinthe aspirators I5.

It will be observed from inspection of Fig. 1 that each aspirator I5consists of a rear cylindrically tubular portion I'l, an intermediatecontracting transitional portion i8 and an expanding portion I9, theouter end of which opens through the wall I6 of the cyclone.

Referring now to Fig. 3, there is extended through the rear end wall 23of each unit I5 a water pipe 2| which terminates in a spray nozzle 22positioned within the contracting portion I8 of the aspirator.

The nozzle 22 is preferably designed to produce a cone-shaped spray suchthat the water issuing therefrom is broken up into very fine particlesand directed at very high velocity into the throat portion 23 of theaspirator which is located at the junction of the contracting portion I8 with the expanding portion I9. The water spray entraps and carrieswith it exhaust gas entering through the branch l3, which gas isdischarged at high velocity through the throat 23 of the aspirator andat the same time is thoroughly intermixed with the finely divided water.

The exhaust gas is almost immediately cooled by contact with the water,the water being simultaneously heated, so that the mixture is at acommon temperature intermediate the temperatures of the spray water andthe exhaust gas as it entered through the branch I The temperature andquantity of spray water are so chosen as to bring the mixture to atemperature at which a substantial portion of the water vapor originallypresent in. the exhaust gas is condensed.

Because of the high velocity of the mixture as it passes through thethroats 23 of the aspirating tubes, the pressure is reduced, but as themixture moves on through the expanding portion I9 of each aspirator, thevelocity is reduced and the pressure correspondingly increased. Afterdischarge of the mixture from the aspirating units into the cyclone Ill,the velocity is further reduced and the pressure is correspondinglyincreased.

As previously indicated, the exhaust gas is so thoroughly mixed with thespray water in the aspirating tubes I5 that substantially all of theexhaust gas is reduced immediately to a temperature very near the finaltemperature it reaches within the cyclone I0, so that most of the watervapor is immediately condensed. A large portion of the condensed watervapor mixes immediately with the spray water and the rest separates inthe form of small dropletssuspended in the gas. Because of the fact thatthe mixture is introduced tangentially into the cyclone II), the mixturerotates rapidly within the cyclone and the resultant centrifugal forcethrows the bulk of the water against the peripheral walls, including theupper cylindrical wall I6 previously mentioned and a lower conical wallwhich extends downwardly and inwardly from the lower edge of the wall I6to a water discharge pipe 28 connected to the lower end or apex of theconical section. As the condensed water flows down the walls of thecyclone, it enters the pipe 26 and is circulated in a manner to bedescribed later.

The residual exhaust gas that is separated from the solid water migratestoward the center of the cyclone and enters the lower end of an outletpipe 21 which extends up through the top wall 28 of the cyclone and isconnected by an elbow 28 to a horizontal pipe 30 which connects to theinlet end of a secondary separator 3|, the outlet of this separatorbeing connected to a discharge pipe 32, the outlet of which dischargesinto the atmosphere. This discharge pipe 32 may contain a damper valve33 for regulating the rate of discharge of the residual gas and therebycontrolling the pressure existing within the cyclone Ill.

As has been previously explained, greater water recovery is obtained athigh pressures within the cyclone Ill than at low pressures, and thedamper 33 is preferably adjusted to maintain the pressure within thecyclone as high as is possible without introducing back pressure intothe exhaust line II. Hence the resistance afforded by the flow of theresidual gas through the pipe 21, elbow 29, pipe 30, secondary separator3!, and the discharge pipe 32 is preferably such as to just balance thepressure developed in the aspirators I5 and thereby maintain as great apressure in the cyclone ID as is possible without introducing backpressure into the exhaust line II.

The lower end of the pipe 21 may be anchored by means of studs 2'extending radially from this pipe near its lower end to the wall of thecyclone.

We have found it desirable to introduce into the lower portion of theconical section 25 of the cyclone a baflle 35 for facilitating thecoalescence of fine water droplets. The bafile has radially extendinglouvers or fins so inclined relative to the swirling gas in the cyclonethat droplets of water in the gas are caught on the under sides of thelouvers, where they coalesce and drop to the bottom of the cyclone.

Water entering the pipe 26 from the bottom of the cyclone I0 isdelivered by a pump under pressure through a pipe 4| to a radiator 42which may be of conventional construction and cooled by atmospheric airintroduced through a scoop Z3 and discharged through a vent member 44,these latter members being so positioned on the aeroplane as to utilizeits motion through the air to circulate cooling air through the radiator42.

From the radiator 42 the cooled water flows through a pipe 45 into asump 46, which sump also receives water through a pipe 41 from thesecondary precipitator 3|. The latter preferably contains baiiies 3which force the gas moving therethrough to travel in a tortuous path andefiect separation of any particles of water that may be entrained in thegas leaving the cyclone II).

It is to be understood that the secondary separator 3| is not alwaysessential and can, in many instances, be advantageously eliminated sincethe separation of the gas from the water within I the cyclone may besufilciently complete.

The sump 46 is provided with two discharge lines 48 and 49. The pipe 48goes to the apparatus for introducing water into the engines and ispreferably located above the bottom of the sump 46, so that it candeliver water only when the supply within the sump exceeds apredetermined minimum amount.

The pipe 49 delivers water from the bottom of the sump 46 to a pump 50which delivers it under substantial pressure through a pipe 5| to thepipes 2| of the four aspirator units l5.

By virtue of the location of the discharge pipe 48 above the bottom ofthe sump 46, enough water is always maintained in the system to fullysupply the nozzles 22 in the aspirator units l5.

As shown in the drawing, thepump 40 is driven by an electric motor 40land the pump 50 is shown driven by an electric motor 50L Obviously,however, any available source of power can be used to drive the pumps.

In some installations it may be desirable to dispense with one of thepumps 40 or 50-. The pump 40 may be dispensed with if the position ofthe radiator is below the cyclone, and the sump 46 is below the radiator42, so that water can flow by gravity from the cyclone through theradiator to the sump, or the pump 50 can be eliminated, and the pump 40designed to provide suifi-cient pressure for forcing the water throughthe radiator and the sump to the jets in the aspirating units.Ordinarily, however, it is desirable to provide substantial pressure inthe water line, as this enables the efficient operation of the systemwith a smaller quantity of circulating water and thereby reduces thetotal weight. High pressure is desirable to increase the rate of fiowthrough the radiator 42 and to provide high velocity of the waterissuing from the nozzles 22 in the aspirating units so as to develop themaximum possible pressure within the cyclone I0.

Although for the purpose of explaining the invention, one applicationthereof as disclosed in the drawing has been described in detail,various departures from the exact structure shown will be apparent tothose skilled in the art, and the invention is to be limited only to theextent set forth in the appended claims.

We claim:

1. In a system for recovering water from the exhaust gas of an internalcombustion engine; a precipitating chamber having gas and water outeltpassages, means for introducing exhaust gas and cooling water into saidprecipitating chamber comprising an aspirator having a water jet thereinfor aspirating exhaust gas into said chamber, and means for supplyingwater tosaid jet under substantial pressure, in which said as- 5pirating means comprises a conduit communicating with said precipitatingchamber, said conduit being of relatively large cross-section at thepoint of its juncture with said chamber and at a second point spacedtherefrom, and being of reduced 10 cross-section intermediate saidpoints, said water jet being positioned within said second enlargedportion for directing a spray of water through said reduced neck portiontoward said chamber, and means for supplying exhaust gas to said conduiton the upstream side of said jet.

2. In a system for recovering water from the exhaust gas of an internalcombustion engine; a precipitating chamber having gas and water outletpassages, means for introducing exhaust gas and cooling water into Saidprecipitating chamber comprising an aspirator having a water jet thereinfor aspirating exhaust gas into said chamber, and means for supplyingWater to said jet under substantial pressure, in which saidprecipitating g5 chamber is of circular cross-section in horizontalplanes, with said aspirating means positioned to direct exhaust gas andwater into said chamber tangentially, said exhaust gas outlet comprisinga conduit extending into said chamber and terminating centrally therein,and said water outlet being located at the bottom of said chamber.

PAUL A. PITT. CLARENCEO. MOE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name I Date 467,264 Raymond Jan. 19, 1892714,080 Whilson "Nov. 18, 1902 793,885 Lowe July 4, 1905 1,152,381Kenney Aug. 31, 1915 1,172,429 Carrier Feb. 22, 1916 1,388,480 Paris, JrAug. 23, 1921 1,875,755 Noyes Sept. 6 1932 1,987,604 Corbett Jan. 15,1935 2,152,251 Gay Mar. 28, 1939 2,222,930 Arnold Nov. 26, 1940 FOREIGNPATENTS Number Country Date 343,587 Germany Nov. 4, 1921

